Index of the gas block to barrel gas port looks good via the burn mark around the barrel gas port.

On the inside of the gas block, check the ridge around the gas block passage channel for a high ridge cause when the passage was drilled that is not allowing the entire top of channel in the gas block to mate correctly with the entire top of barrel.  If needed flush the ridge with the ID of the gas block channel.


Also, when the gas block is installed on the barrel, the set screws that secure the block to the barrel have to be loctite in place.  red 272 is the correct loctite, and if the allen screws need to be removed later, the insert a old allen wrench in the allen socket heads, Glow the wrench with a torch to heat the screws up to break down the loctite bond, then switch over to a new allen wrench to remove the set screws.

As for checking for leaks, CLP sprayed around the gas tube to block front and back, gas block to barrel front and back, and then use a piece of tubing on the end of the gas tube in the receiver to pressurize the gas tube to 100lb of air.  Also, check the carrier key for leaks as well, hence CLP around the base of it where it sits on top of the carrier, then hold the bolt inward while pressurizing the front of the key.   You should not have any leaks from the gas tube to key, block to barrel, nor key to top of carrier.

But back up, and bring me up to speed on the reason for the adjustable gas block in the first place.

Thought the answer to your problem was pretty straight forward.
Return the Seekins Precision Adjustable Gas Block  back to the supplier to either get you one that is not leaking, or find another brand of adjustable gas block if you just must pimp the rifle with an adjustable gas system.



The barrel gas port size is set for a zero leak gas block, so any leak in the block means that the rifle is going to short stroke since you will not have enough pressure to the action gas system.  Better yet, an adjustable gas block is only used when you are using ammo (such as in the case of 69gr rifle) that is going to create greater then norm action gas port pressures from the slower burning powder/ running a suppressor where the back pressure from such in the barrel bore will greatly increase the action pressure on the standard size barrel gas port size, and the problem is better solved with just increasing the buffer weight or Increasing the recoil spring tension.

Furthermore lets really back this up, a rifle will run fine with all standard components, and lets play  lets wrong with your set up for 55/52gr ammo to begin with.
The Adjustable gas block in the first place is not needed for the ammo you ran, the extra tension spring is going to cause short stroking, then the leaking gas system, just a couple of more final nails in the coffin lid of why the rig is not running correctly.